Water soluble dye salts and process for the production thereof



l. e; t,

action, e. g. an alkyl or an ether group.

United St WATER SOLUBLE DYE SALTS AND PROCESS FOR THE PRODUCTION THEREOF 5 No Drawing. Application December 12, 1955 Serial No. 552,294

Claims priority, application Switzerland December 15, 1954 6 Claims. (Cl. 260146) The invention concerns water soluble dye salts containing an azo dyestufl as cation and processes for the production thereof from azo dyestufis which contain a benzthiazole ring and which are insoluble in water.

It has been found that stable, water soluble dye salts which contain the azo dyestufi as cation are obtained if anazo dyestuff having no acid dissociating, salt forming groups, of the general Formula I the carbon rings, one of which at least must not represent hydrogen. The group represents an amino group and R and R thus represent hydrogen or aliphatic, araliphatic, aromatic and alicyclic substituents. Of R to R two neighbouring substituents can also form a ring, for example an isocyclic or a heterocyclic ring.

In the dyestuffs according to the present invention, R represents preferably a substituent with a positive It can also represent methyl, ethyl, isopropyl, tert. butyl, tert. amyl, 0 methoxy, ethoxy, phenoxy, benzyloxy groups in addition to methyl mercapto or phenylmercapto groups as well as groups forming a ring with a neighbouring substituent such as the dihydroxymethylene group, tetramethylene group or the dioxine ring. Valuable greenish-blue dyestuffs are also obtained if a neighbouring pair of R to R represent a fused benzene ring. In other respects however, the benzene ring of the benzthiazole radical can be substituted within the bounds of the definition as desired, e. g., by halogen, nitro, acylamino, alkyl sulphonyl, carboxylic acid ester, sulphonic acid amide, phenyl or benzyl groups. The p-phenylene radical bound to the azo group can form part of a fused ring system. Either the pair of substituents R and R or the pair R and R can be bound to form rings in such a manner that 5 they can represent either a fused benzene ring or a hydrogenated isocyclic or heterocyclic ring. For example with the p-phenylene radical they can form a naphthalene radical, a tetrahydronaphthalene radical, a benzimidazole, benztriazole or indazole radical. Advantageously however, R to R represent two hydrogen atoms'in the pposition to each. other, as p-aminobenzene azo dyestuffs atent are particularly valuable. In a preferred group from this class of dyestuffs according to the present invention, R is a substituent usual in azo dyestuffs, e. g. 'an alkyl, alkoxy, acylamino group or a halogen atom. However, it can represent a more negative group such as e.g. an alkyl sulphonyl and the nitro group. If R is an alkyl or an alkoxy group, the amino group in the p-position can be primary, otherwise it is substituted, preferably organically, i.e. it is either a secondary or advantageously a tertiary amino group. Organic substitutents of the amino group can be aliphatic, araliphatic, cycloaliphatic or aromatic, the heterocyclic-aliph atic groups like the furyl methyl group also being understood by the term araliphatic. The organic substituents can be further substituted, such as for example in the oxalkyl, fluoralkyl, cyanalkyl, alkoxyalkyl, phenoxyalkyl, the alkylbenzyl, halogen benzyl, alkoxybenzyl, alkylphenyl or alkoxyphenyl groups. Aliphatic substituents of the amino group can also form hetero rings among themselves, possibly in cluding ether atonrs or linked to the substituents R and R such as in the piperidino, morpholino, the 1.2.3.4- tetra'hydroquinoline, the lilolidine, the julolidine or the perimidine compounds. One of the two nitrogen substituents is advantageously a cyanethyl, benzyl, or phenyl radical. Thus, whilst the azo dyestuffs usable according to the present invention can be further substituted with non-ionogenic substituents as desired, acid dissociating salt forming groups such as for example the carboxyl and the sulphonic acid group are excluded as substituents.

Alkylating agents suitable for the production of the dye salts according to the present invention are the esters of strong mineral acids and organic sulphonic acids of preferably lower alcohols. Alkyl chlorides, alkyl bromides, alkyl iodides, aralkyl halides such as benzyl bromide, benzyl halides substituted at the benzene ring by halogen, alkyl or alkoxy groups, dialkyl sulphates and alkyl-p-methyl benzene sulphates are chiefly used. The azo dyestuffs usable according to the present invention are reacted with the suitable alkylating agents advantageously in inert organic solution, the water soluble dye salts separating out. Examples of solvents are benzene hydrocarbons, halogenobenzenes and nitro benzenes, high boiling aliphatic and alicyclic hydrocarbons as well as stable halogen alkanes such as carbon tetrachloride, tetrachlorethylene. Also an excess of alkylating agent can be used as solvent. The reaction is exothermic. To start the reaction, however, warming is necessary in particular when there is a large amount of diluent. In some favourable cases however, salt formation also occurs in aqueous or alcoholic solution or suspension, the dye salts formed being dissolved and isolated by salting out. if the reaction is performed in organic solvents, these can be removed by filtration or, due to the stability of the dye salts according to the present application, they can be removed either by distilling olf, possibly under reduced pressure or by steam distillation. The dye salts according to the present invention can be obtained from organic solution also byextraction with water. It is of advantage to use an excess of alkylating agent, whereby any primary and secondary amino groups can also be subsequently alkylated. However, the formation of the cyclammonium salt is clearly preferred so that under the usual working conditions dyestuifs do not result which are similar to those with a tertiary p-amino group, from analogous dyestuifs with a primary or secondary p-amino group. If necessary, the dye salts according to the present invention can also be modified subsequently, for example, they can be acyla-ted. 7

Some of the dyestuffs usable according to the present invention are known, others can be produced by methods knownper Se by diazotising Z-aminobenzthiazole comin the p-position to a primary, secondary :or tertiary amino group, or by alkaline condensation of p-nitroso 'aminoaryl compounds with Z-amihobenzthmzole cornattained with the dyestuffs according to the present in- I vention are often distinguished by their fastness to light.

The following examples serve to illustrate the invention. Where not otherwise stated, the parts are given as pounds. a 5 parts by weight and the temperatures are in degrees The die'salts according to the present inventi n havcentigrade. The relationship of parts by weight to parts ing no acid dissociating, salt forming groupsin the cation, by volume is as that of kilogrammes to litres. correspond to the general Formula II: Example 1 R1 i T A diazo solution is prepared from 18 parts of Z-amino- R 6-1nethoxy benzthiazole, 300parts of 60% acetic acid, 9 I 20" parts of concentrated-sulphuricacid and 34 parts of C nitrosyl sulphuric acid, corresponding to 6.9 parts of I Rm sodium nitrite. A solution of 15.3 parts of 1-amino-2.5-

R5 dimethoxybenzene in IOOparts of glacial acetic acid is in) added dropwise at 15 to 5 to the diazo solu- In hi rm 11 t r s n alkyl radical, hi tion. After stirring for 2 hours, 300 parts of water are can be further' substituted, e.g. aurnethyl, ethyl, propyl, added to the coupling mass and the miueralacid rey s y beniyl, p-methylb y i i 1 s action is buffered with lye until Congo red paper is no represent the? I10n-i0n0geBi spbstituents', lud ng y longer coloured blue. The precipitated brown-violet dyegen, attached to the carbon'rings, of which at l a 0 stuff is drawn oil under suction, washed with a lot of must not'be hydrogen, e.g. alkyl, alkylene, .phenyl, benwater and driedin the vacuum at 7 0, y halogen. ether. nitro, y m y p y 3.5 parts of the well dried dyestuii are heated for 5 sulphonic acid: amide,- carboxylic acid ester or calibQ yl 1 hours underpressureat 120-140 with4.4 parts of ethyl. acid amide substiments, 9 Rmiepfesent y g bromide in 200 parts of abs. alcohol in'the presence Of, or organic substituents, e.g'. alkyl, alkylene, 'aralkyl, cy- 0.8 part of magnesiumoxide. The greater part of the cyloalkyl, phenyl substituents, whereby of R to R tW solvent is then distilled off in the vacuum. To further neighbouring substituents can togetherforma ring which purify, the residue is taken up in 250 partsot warm water can be isocyclic, eg. a fused benzenering, a tetramethyland the solution is clarified with a little animal charene group, or. it can be heterocyclic e; g. a methylenecoal. The'dyesaltis precipitated from thefiltered soludioxy ring, a dioxine ring, a triazole, imidazole, pyra tion. with 1.5 parts of zinc chloride and 25 parts of so-. zole ring, or with R and R it canalso bea piperidino, dium chloride; .Aftcr drawing off under suction and morpholine or tetrahydro-pyridine ring. X represents drying, the dyestuif dissolves in Water with a blueand the uncoloured anion equivalenttothe; coloured cation, in concentrated sulphuricacid with a yellow'coloun; It 45 Chlorine ions'bl'omine'mn, n6 i011. methosulphate dyes silk, leather, mordanted cotton and polyacryloniion, ethosulphate ion, bisulphate ion, sulphate ion, bcn- 'trile fibers from'an acetic acid solution in violet shades zenc sulphonate ion, p-toluene .sulphonate ion; it can which have good fastness properties. I however, also represent ions of stronger organic acids, Products with similar properties areobtained if, keepe.g. ionsof acetic acid, formicacid oxalic acid, lactic 'ing to the above conditions, the alkylation is performed acid,tartaricacid, chloracetic aid, sulpho-acetic acid and 40 with the corresponding amounts of benzyl bromide, possibly even the hydroxyl ion. I The productionand use methyl iodide, ethyl iodide or n-butyl iodide.

of the double salts with inorganic'salts is often advan- Dyestuffs with similar properties are obtained if the tageous, in particular the zinc chloride double salts. Thus above diazo component is coupled to form the monocornplex anions can be used as anions equivalent to the azo dyestuff with the coupling components given in the caiton, e.g. the halogenozincate cation. As can be seen, following table and the amounts of substances given the uncoloured anion X is of secondary importance; the are used and otherwise the same procedure is followed. dyestuff character is determined by the cation. But it The same products are also obtained if the alkylation is favourable for the water solubility if X represents one is performed in boiling tetrachlorethane with dimethyl of the anions of strong acids first listed above. sulphate, diethyl sulphate etc.

Parts Parts Dyeing on No. Coupling component dyesol- Alkylating agent polyacrylostufi vent nitrile fibres 1 Aminobenzcne 2.9 200 4.4,partsethylbromide. Violet 2 1-amin0-3-n1ethy1benzene. 3.0 200 -do Do.

3 l-amino-B-ehloro-benzene-. 3.2 200 1.6 partsmethyliodide D0. 1-amin0-3-methoxybenze11e. 3.2 250 4.4parts ethyl bromide Do. l-amino-S-aeetaminobenzene 3.4 250 --.do D0. Lamina-2.5-dimethylbenzenc- 3.1 200 2.0partsn-butyliodide- Dc. 1-amino-2-methoyx-5-methy1benzene- 3.3 200 0 D0.

l-amino-2-methoxy-5-ucetaminobenzene- 3.7 250 4.4 parts ethyl bromide Do.

N-ethy1-N-benzylaminobenzene 3.9 250 .do Blue 1 The dyestufi is obtained by coupling with the sodium salt of methylaruinobenzene-w-su1phonic acid and then saponifying to form the p-amino-monazo dyestuti.

According to their charactenthe dye salts according to the present invention can be described as basic dyestufis. Particularly in the formof salts of strong inorganic and organic acids they dissolve well in water. Less easily soluble compounds can be dissolved in diluted aqueous mineral acids. In aqueous solution, the dye salts according to the present invention dye cotton mordanted with tartar emetic and tannin, silk, leather and synthetic polymeric fibres containing nitrogen which are produced from polyacrylonitrile or chiefly from Example 2 A solution of 20 parts of 2-amino-(naphtho-1.2:4.5)- thiazole'in20 parts of acetic acid is added to a mixture acrylonitrile, generally in very pure shades. The dpeings which has been cooled to +-l0 of 220 parts of sulphuric 5 acid 60 B6. and 150 parts of water. It is diazotised Within 2 hours at 10 with 13.4 parts of nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite and, after stirring the reaction mass for half an hour, it is poured into 1500 parts of ice water. A weakly aqueous/rnineral acid solution of 13.3 parts of N-ethyl-N- benzyl-arnino-benzene is added to the clarified diazo solution at -5, the reaction is buflered until it is neutral to Congo red paper and the brown-violet dyestuif which precipitates is drawn off under suction, Washed and dried.

10 parts of p-toluene sulphonic acid methyl ester in 20 parts of xylene are added dropwise at 110 within minutes to a solution of 4.2 parts of this dyestulf in 200 parts of xylene. 'The reaction solution is kept for 45 minutesat llO-l20. After cooling to 0", the pure dyestuff obtained is drawn off under suction. It dissolves in concentrated sulphuric acid with a brown-red and in water with a blue colour. It dyes polyacrylonitrile fibres, silk, mordanted cotton and leather from an acetic acid bath in vivid blue shades which have good fastness properties.

Similar dyestuifs with the same good properties are obtained if instead of N-ethyl-N-benzyl-aminobenzene, N.N- dimethylaminobenzene, N.N-diethylaminobenzene, 1-N.N- diethylamino-3-methylbenzene, N.N dibenzylaminoben- "6 mixture for some time, 300 parts of water are added and the mineral acid reaction is bufiered with sodium acetate. The brown-violet dyestutf which precipitates is drawn 01f under suction, washed and dried'in the vacuum at 70.

1.9 parts of dimethyl sulphate in 10 parts of chlorobenzene are added dropwise at boiling temperature within 1 hour to a solution of 4.1 .parts of this dyestutf in 100 parts of chlorobenzene. A change in colour from red-violet to blue of the solution and precipitation of the dyestufi can be observed. After cooling the reaction mass, the precipitated dyestuff is filtered oil and, to further purify, is dissolved in 250 parts of hot Water and precipitated with sodium chloride from the solution which has been clarified with a little animal charcoal. The dyestufr is drawn oil under suction and dried. It dissolves in concentrated sulphuric acid with a yellow and in water with a blue colour. It dyes polya'cryonitrile fibres, silk, leather and mordanted cotton from'an acetic acid bath in vivid blue-violet shades which have good fastness properties.

If in the above example, instead of l-N-ethyl-N-benzylamino-3-methoxybenzene the equivalent amounts of the coupling components given in the following table are used and the amounts given of alkylating agent are used, then dyestuffs with similar properties are obtained.

No. Coupling component Parts Parts dyesolstufi vent Dyeing on polyacrylo- Alkylating agent nitrile fibres chlorobenzene.

1-N.N-dlethylamino-3-methylbenzene-.. 3. 4 120 1 N.N-diethylamino-3-aeetaminoben- 3.9 120 1 diethylamino-3-earbethoxyben 4. 0 1 l iN di-B eyanethylamino-El- 4.1 150 2.1 partsp-toluene sul- Red-Blue.

plzgmic acid methyl ester. 0'.

150 do Do.

1.9 parts dlemethyl sul- Do.

phate.

N.N-dl-B-oxethylaminebenzene N.N-dibenzy1amino-benzene N -methyl-N -B-oxethyl-arntnobenzene N methyl-N-fi-cyanethylaminobenzene- ....d0 do 2.1 pants diethyl su1phate-- on.

1 -N.N-dimethylamino-3-nltrobenzene 3 N.N-diet;hylamino-benzene sulphonic acid dimethylamide.

4 5 8 3 3. 4 N ethyl-N -benzyl-aminobenzene 2 1 N.N-dipropylamino-3-bromobenzene- 4 3 200 1.9 parts dtmethyl snl- Do.

phate.

300 do Do.

250 2.1partsdiethy1sulphate Do.

zene, 3-N.N-diethylaminobenzene-1-su1phonic acid amide are used or if 2-amino-(naphtho-1'.2:5.4)-thiazole is used as diazo component.

Example 3 A diazo solution is produced from 16.4 parts of 2- amino-6-methy1 benzthiazole, 300 parts of 60% acetic acid, 20 parts of concentrated sulphuric acid and 20 parts of nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite. A congo acid solution of 24.9 parts of l- N-ethyl-N-benzylamino-3-methoxybenzene in the equivalent amount of 2-N-sulphuric acid is added at 15 to 5 to the diazo solution. After stirring the coupling The dye salts obtained with all the coupling components given in the above table all dissolve in water with a blueviolet and concentrated sulphuric acid with a yellow colour.

Example 4 The monoazo dyestufi from 2-amino-6-ethoxy benzthiazole and l-N-ethylamino-3-methylbenzene is produced as described in Example 1.

3.4 parts of this dyestuif are dissolved in parts of abs. toluene and 2.1 parts of diethyl sulphate in 10 parts of abs. toluene are added at The reaction mixture is boiled under reflux for one hour. After a few minutes the solution turns blue and therdye salt gradual- Parts Parts Dyeing on No. Coupling component dyesol- Alkylating agent polyaerylostufi vent nitrile fibres 1 l-N ethylamino-l-chlorobenzene 3.6 200 2.1 parts p-toluene sul- Violet.

- phorueacidmethylester. 2 1-N-ethylamjno-3methoxybenzene 3.4 200 1.9hp arts dimethyl sul- Do.

- p a e. 3 l-N-ethylam no-ti-ethoxybenzene 3.6 200 do Do. 4 l-N-methylamino-3-aeetaminobenzene.. 3.5 200 '2.1 parts p-toluene sul- Do.

- I e e a v phonic acid methyl ester. 6 1-N-ethylamlno-2.5-dimethoxybenzene.. 3.7 200 do Do. 6 1-N-ethylam1'no-2.delimethylbenzene. 3.4 200 .do D0. 7 1-g I-methylamino-2-methoxy-fi-methyl- 3.6 200 1.9 parts dimethyl sul- D0.

enzene. r r p e. 8 1 N methylamino-2-methoxy-5- 3.9 250 2.1 parts diethyl sulphate. Do.

acetaminobenzene. 9 Diphenylamine 5.0 250 do Blue. 10 l-N-ethylamino-3carbethoxybenzene. 3.9 .do Violet.

ly precipitates in crystalline form. The blue-black dyestufi. so obtained is filtered off after the reaction mass has been cooled. To further purify, the dyestufi is dissolved in 200 parts "o'f'warn'i Water and is precipitated in the cold with 30 parts of'sodium chloride. It dissolves in water with a violet and in concentrated sulphuric acid with a yellowish colour. The dyestuif dyes silk, mordanted cotton, and polyacrylonitrile fibres from an acetic acid bath in violet shades which have good fastness properties. i

Dyestuifs with similar properties are obtained if dyestuffs are alkylated which have the corresponding amounts of the monoalkylated anilines given in the following table as coupling components instead of 1-N-e'thyl-amino- 3-methylbenzene and the amounts of substances given in the table are used and the conditions desribed are kept.

The dye salts obtained with the coupling components Nos. 1 to 8 inclusive and with No. 10 all dissolve in water with a violet and in concentrated sulphuric acid with a yellow colour. That obtained with coupling component No. 9 dissolves in water with a blue and in concentrated sulphuric acid with a yellow colour.

Example The monoazo dyestufi from 2-amino-6-ehlorobenzthiazole and 1-N.N-dimethylaminonaphthalene is produced as described in Example 3. A solution of 3.6 parts of this dyestuff in 200 parts of abs. alcohol is heated under pressure for 2 hours at 120 with 4.4 parts of ethyl bromide. The reaction mixture is evaporated to dryness and the residue is worked up as described in Example 1. The dye salt isxdried in the vacuum at 70. The blueblack dyestufi dissolves in concentrated'sulphuric acid with a yellow and in water with a blue colour. It dyes polyacrylonitrile fibres, mordanted cotton and silk from an acetic acid bath in vivid red-blue shades. Dyeings of the same shade are obtained with the Zincchloride'double salts.

Similar shades are obtained with the alkylated dyestutfs which are produced from the same diazo compound and the following coupling components: l-N- phenylaminonaphthalene, 1-N.N-dimthylamino-Z-methoxynaphthalene or 1.2.3.4 tetrahydro-5.6-benzoquinoline.

Example 6 16.4 parts of 2-arnino-4-rnethyl 'benzthiazole in 200 parts of sulphuric acid 60 B. and 150 parts of water are diazotised within 2 hours with 25 parts of nitrosyl sulphuric acid which correspond to 6.9 parts of sodium nitrite. The clear diazo solution is diluted with 1000 parts of ice water and a solution of 18.3 parts of N- methyl diphenylamine in 200 parts of 15% sulphuric acid is slowly added at 0-5. The whole is stirred for 3 hours, then the mineral acid reaction is buffered with saturated sodium acetate. solution until Congo red paper is no longer coloured blue. The red dyestufl which precipitates in crystalline form is filtered oflf, washed with a lot ofwater and dried in the vacuum.

The dry dyestuif is converted into the corresponding cyclammonium salt with dimethyl sulphate in boiling chlorobenzene as described in Example 1. The dark blue methylation product dissolves in water with a blue and in concentrated sulphuric acid with a yellow colour. It dyes polyacrylonit'rile fibres, mordanted cotton, silk and leather from an acetic acid bath in vivid blue shades which have good fastness properties.

' Similar fast dyeings are obtained if alkylated dyestuffs are used which have the following 2-amino benzthiazole derivatives as diazo components instead of, 2-amino-4- methyl benzthiazole: 2-arnino-6-ethyl benzthiazole, 2- ainino-G-phenyl benzthiazole, 2-amino-6-chloro benzthiazole, 2-amino-6-carbethoxy benzthiazole, 2-amino-6- methoxy benzthiazole, 2-amino-6-ethoxy benzthiazole, 2- amino-6-methyl sulphonyl benzthiazole, 2-amino-4-chloro benzthiazole, 2-amino-4-ethy1 benzthiazole, 2-amino-6- thiocyano benzthiazole, 2amino-6-cyano benzthiazole, 2-

amino-4-bromo benzthiazole, 2-amino-(naphtho-l.2: 4.5 )-thiazole or 2-amino-(naphtho-1.2:5.4)thiazole.

Similar blue dyestuffs are obtained if, in compounds produced with the above diazo components, corresponding amounts of jtriphenyl amine are used as coupling component and the alkylation is performed as given in the above'exarnple.

Example 7 V A diazo solution is prepared from 15 parts of Z-aminobenzthiazole, 300 parts of acetic acid, 20 parts of concentrated sulphuric acid and 20 parts of nitrosyl sulphuric acid, corresponding to 6.9 parts of sodium nitrite. A Congo acid solution of 2.2 parts of l-N-ethyl- N-benzylamino-3-bromobenzene in the equivalent amount of Z-N-sulphuric acid is added dropwise at 15 to 5 to the diazo solution. After stirring the coupling mixture for 2 hours, the mineral acid reaction is buttered with concentrated causticsoda lye until Congo red paper is no longer coloured blue. The red dyestuif is drawn off under suction, washed with a lot of water and dried in the vacuum at Products with similar dyeing properties are obtained starting from monoazo dyestuffs which are produced in an analogous manner with the coupling components given in the following table and otherwise by keeping to the above, conditions and using the amounts given inthe following table.

Coupling component Parts dyesolstufi Part Dyeing on polyacrylo- Alkylating agent nitrile fibres vent Lamina-2.6-dimethy1 benzene l-amino-Znncthoxybenzene l-N-ethylemino-3-methylbenzene l-emino-Zjdimethoxyb enzene 1 N.N dimethylamino 2.5 dimcthyl benzene. 1 N.N di n propylamino 2 ethoxy 5- methylbenzene. 1 N.N di -n butylamino 2 methoxy S-acetaminobenzene. l-N.N-diethylamino-3-acetaminohenzone 1 N methyl fl eyanethylamino 3 methylbenzene. I 1-N-ethylamino-2.E-dichlorobenzene l-N.N-dimethy1amino-3-nitrobenzene 1 N.N diethylaruino 2 methyl 5 methyl sulphonyl benzene. 1 N.N diethylaminobenzene 3 sul phonic acid amide.

Violet.

Blucwiolet. Violet.

Blue-violet.

Reddish blue. Red-blue.

2.1 parts p-toluene sulphonic acid methyl ester.

1.9 parts dimethyl sulphate.

do Blue-violet" 2.75 parts p-toluene sul- Violet phdonjc acid ethyl ester. o

275 parts p-tbluene sulphonie acid ethyl ester. 2.1 parts diethyl sulphatephate.

2.75 parts p-toluene sulphonic acid methyl ester.

3.8 parts of this monoazo dyestuif are dissolved in 150 hetero ring, R represents a member selected from the parts of absolute chlorobenzene and 1.9 parts of diclass consisting of lower alkyl and benzyl radicals, and methyl sulphate in 50 parts of chlorobenzene are added wherein of R to R at least one is other than hydrogen, at the boiling temperature of the solvent. The reaction and X represents an anion. solution is boiled for one hour during which time the 5 2. Adyestufi of the formula:

colour changes to blue and the dye salt gradually pre- 3, A dyestuff of the formula: cipitates. After cooling the reaction solution, the pre- CHa cipitated dyestuif is filtered off, taken up in 200 parts I I 1 of warm water, the aqueous solution is clarified with a CH5 little charcoal and the dye salt is precipitated with the aid I of 1.5 parts of zinc chloride and parts of sodium 20 C N=N O N O1 Znoh chloride in the form of the zinc chloride double salt. GHaO- The yellow-bronzy powder so obtained is dried in the vacuum at 6070. It dissolves in water with a blue and 4. A dyestufi of the formula:

in concentrated sulphuric acid with a yellow colour. It 5. Adyestutf of the formula:

dyes silk, mordan-ted cotton and polyacrylonitrile fibres I OHOHB in vivid red-blue shades which have excellent fastness l properties.

All the products obtained with the coupling components CH Zn C1 given in the above table dissolve in concentrated sul- 3 phuric acid with a yellow colour. S NO,

What we claim is:

1. A dyestuif of the formula: A dyestufi of the formulai' GB (imam 69 R1 N a, R c n. B

0 I R1 CHao s s R a References Cited in the file of this patent wherein the cation is free from acid salt-forming groups, UNITED STATES PATENTS R to R each represents a member selected from the 2135 293 Renshaw et aL Nov. :1 1938 class consisting of hydrogen, chlorine, bromine, lower 2:441:612 Argyle et a1. May 1948 alkyl, lower alkoxy, phenyl, carbo-lower alkoxy, sulphonic acid amide, lower alkylsulphonyl, nitro, acetyl- FOREIGN PATENTS amino, w and thiocyano groups each of the 136,921 Switzerland Feb, |17, |1930 pairs R and R and R and R together also may repre- 1,049,896 France Aug 2 95 sent a fixed benzene ring, R and R; each represents a OTHER REFERENCES member selected from the group consisting of hydrogen, lower alkyl, benzyl and phenyl radicals, and each of the Saunders: The Aromatic Diazo-Compounds (2nd ed.), pairs R Rq and R R together also may complete a 1949, pp. 78-79. 

1. A DYESTUFF OF THE FORMULA 